I usually avoid Dylan's Candy Bar at Third Avenue and 60th St., since most of the time it's packed with kids and tourists. But my 85 year old mother and I went on a lark-- and she loved it! I finally lost my grumpiness as well when they started playing "Sugar, Sugar" (still one of my fave songs). Dylan's is-obviously-heaven for kids, but really it is fun for everyone. Let's face it-adults like candy as much, if not more than, kids. And they have a "nostalgia" section where you can find Sky Bars, Teaberry Gum, Buns, Mallo Cups, and more.
Another plus--the service is VERY friendly. Clearly the kids they hire are well-trained in customer management and they are patient and helpful.
Bulk candy runs $10.99 a pound, and they also have fudge, and a sweets cafe upstairs with ice cream and cupcakes (the cafe looked a little sterile however).
Lots of fun for the kid in all of us.